Valve transmitter arrangement



`June 9, 1931. w. KuMMERl-:R

VALVE TRANSMITTER ARRANGEMENT Filed Dec. 15, 1928 @nom/1to1, mLHELM KUMMEKER Patented June 9, 19131 vnarran STATES PATENT carica WILHELM KUMMENER, on BERLIN, GERMANY, AssIc-.Noa To TNLEFUNKNN GESELL- scrrerT FR DRAHTLosE, TELLGNAPHIN M. B. n.; or BERLIN, GERMANY, A .oon-

PORATION OF GERMANY VALVE TnANsMITTER ARRANGEMENT Application filed December 15, 1928, Serial No. 326,277, and in Germany December 29, 1927.

In radio ytransmission work, it is known that detuning of a circuit in parallelresonance by unilaterally transferred reactive or non-reactive resistance takes placewhen any changes occur in the active resistance4 transferred from the load circuit. e

It is the object of this invention to pref vent this undesired occurrence regardless of the changes inthe load circuit. I y This and other objects of they invention will appear in the following specification when read in connection with the drawings -in which:

Figure 1 shows diagrammatically one preferred embodiment of the invention applied toa tube transmitter arrangement;

Figure 2 diagrammatically illustrates the invention applied to a pushepull arrangement;A Y v Figure 3 shows a modification ofthe invention as applied to different circuits; and,

Figure 4 illustrates vdiagrammatically an oscillation circuit for purposes Iof deriving certain formulae in the annexed specilication. Referring to Figure 1,2 represents the tube working upon a parallel circuit comprising' a coil 5 and a condenser 4..- In suchY fa case should the coupling between the antenna 1 and the working circuit be altered, an alteration of the resistance thus` transferred tothe working circuit will occur. vTo insure optimumfoperation o-fa thermionic-tube, it is necessary to cause the same to work upon an ohmic resistance. Hence, in order that these conditions may be fullled, the working-circuit associated with the tubemust be tuned to parallel or current resonance instead of to voltage or series resonance. These two forms of tuning differ from each other in that voltage or series resonance is not disturbed by a t series resistance in the circuit,v but by aresistance being connected inparallel eitherto the condenser or to the coil, while inversely, that is, in the case of parallel ory current resonance, a resistance disposed in parallel relationship to the oscillation circuit will 'not disturb the resonance condition, whereasan additional resistance connected inv one ofthe branchesyvill lead vto adetuned condition.

Generally speaking, in bjothbranches the voscillation circuit.

resistances are: different, parallel resonance will be present whenever the wattless or reactive components of the currents in the inductive branch and the capacitive branch are equal and opposite. Now, inasmuch as under practical working condition, as shown in Figure 1, the useful resistance is mostly transferred'by transformer action only into one of these two branches,'it will be seen that in such case, even in the presence of tuned condition of the consumer circuit to the operating wave (that is, in the absence of transferred reactance), untuning of the transfer of non-reactive resistance, with the result that the oscillation circuit, considered as a .f

whole, would representa non-ohmic resistance, and this of necessity would be conducive to an impairment of efficiency of the outfit. i

Now, in orderV to pre-clude this change in the characterof the load resistance, a supplementary reactance is provided in series with the oscillation circuit having the same value as the reactance of ythat branch into which non-reactive resistance is not transferred 1' and which is of opposite sense. In this way, as will be noted, the inductive or capacitive load represented bythe oscillation circuit is just compensated. (If the non-reactive resistance is transferred to the inductive branch, then the oscillation circuit constitutes a capacitive'load, whilewhen it istransferred to the capacitive branch, the oscillation circuit represents an inductive load.) i

In the circuit arrangementshown in Figure 1, this additional reactance consists of a choke-coil 3 whose inductance must be chosen vso high that, for the working frequen# cy, it represents au equally high, but oppo site, resistance compared with the condenser.

Calculation shows kthat this compensation `method ofthe reactive resistances (react- Aances) is-independent of the value of the non-reactive resistance in one branch of the if it is kept `in mind that by the change in the' transferred non-reactive resistance, the

This will become clear f current supplied from the generatorv must undergo an alteration, this change in the current supply taking place 1n Vsuch a way that the wattless component of the potential set up across the reactance connected in the plate lead is always equal to and opposite the wattless component of the potential which originates from the untuning of ,the working circuit.

The feature of the invention may be proven mathematically as follows:

In Figure 4, R represents the resistance as applied from the outside, Z2 is the sum of Z1+R the remaining references being selfexplanatory. In the figure, the total 1mpedance of the circuit ZcZz But as described above, Z1, is made equal and opposite to ZC, hence therefore total impedance ZCZL+Z2(ZL+ZC) Z1+Z2 substituting from above total impedance ZCZL Ze Z2 But l co0 therefore substituting total impedance and. ZL :COL

Since Zc V+ Z1 =i O (tuned circuit) Since is a pure resistance then for any value of R obviously it remains a pure resistance. Another suitable scheme is not to simply use a choke coil as shown in Figure 1 or a condenser to represent the reactance but rather a parallel arrangement of a capacity and a choke coil whose total reactance must then be chosen as described above. The use of such a parallel scheme offers the advantage that the chances of disturbing oscillations vof higher frequency beingV formed are precluded since for these frequencies the condenser constitutes a short circuit. It is of advantage to so choose the Vproportions of the choke coil and the parallel condenser that the circuit formed by these two elements is tuned to a frequency located between the working frequency and the next harmonic. A circuit illust-rating the above described parallel circuit is shown in Figure 2 which also illustrates another embodiment of the basic idea when tubes in push-pull are employed.

Figure 2 illustrates another embodiment of the basic idea by way of example. In said ligure in which two tubes 6 and 7 connected in push-pull fashion are provided the reactance circuits 8, 9 comprising a parallel arrangement of inductance coil and condenser are inserted in the two plate leads of the two tubes 6 and 7 since ina circuit such vas shown in Figure 2 the filament lead is not passed or bridged by the fundamental waves as is the case in Figure 1 where, of course, it is immaterial whether the choke coil is disposed at the plate or at the filament end.

The circuit schemes here illustrated and described represent the simplest instances in which the invention will be found useful. In the majority of cases, a complex system comprising several coils and condensers is associated with the electrodes of a transmitter tube. In this case, the compensation scheme here disclosed must, in an analogous Way, be generalized, for instance, in an arrangement as shown in Figure 3 and as used, for example, for short-wave tube transmitters. I-Iere the reactance which is connected in the plate circuit, in absolute value must be equal to the reactance of the equivalent inductancev and equivalent capacity constituted by the coils and condensers as a whole and which are connected with the branch into which the nonreactive resistance is being transferred.

Hence, according to Figure 3 the value of the inductance 10 would be equal to the capacitive Vvalue of the reactance due to the element-s boxed by the dash lines. In complicated cases, as will be noted, the arrangement must be reduced to terms of the simplest or fundamental case, and then the resultant capacity or the resultant inductance must be considered.

Having thus described by invention what I desire to protect by VLetters Patent is as follows:

l. In a transmitting device, an oscillation circuit comprising an inductive branch and a capacitve branch n parallel, an' antenna circuit coupled to one of said branches and a reactance in series with said oscillation circuit having a value equal and opposite to the reactance of the other branch.

2. In a device of the kind described, a parallel resonance circuit, a load circuit coupled thereto and means comprising a reactance circuit in series with said first named circuit for preserving the tuned state of said parallel resonance circuit regardless of the value of any active resistance transferred from said f load circuit to said parallel resonance circuit. 3. In an oscillation circuit comprising a space discharge device having an input and an output circuit, said output circuit compris` thereoil being equal and opposite to the reactance of the other branch of said parallel resonance circuit.

WILHELM KUMMERER. 

